同名RecordGridを何度も生成したときの挙動

[da-itoh]

以下のように呼ばれる度にVboxをクリアして同じ名前のRecordGridを追加するメソッドを作ったのですが、
２回目以降に呼ばれた際にグリッドのヘッダにcaptionの値が表示されません。
同じロジックでRecordGrid.nameを毎回違う名前にすると正常に動作するため、
追加した同名のRecordGridが残り続けていてそれが原因になっているのでは？と思ったのですが、
解決方法がわかりましたらご教授願います。

field package vb-detail-area:VBox
{method private {get-rg first-time?:bool}:void
let fields:{Array-of RecordField} = {new {Array-of RecordField}}
let rgc:{Array-of RecordGridColumn} = {new {Array-of RecordGridColumn}}

{self.vb-detail-area.clear}
{if first-time? then
{rgc.append {RecordGridColumn "row-header"}}
{rgc.append {RecordGridColumn "detail-amount-1"}}
{rgc.append {RecordGridColumn "detail-amount-2"}}
{rgc.append {RecordGridColumn "detail-amount-3"}}
{fields.append {RecordField "row-header", caption = "", domain = String}}
{fields.append {RecordField "detail-amount-1",caption= "初回１"}}
{fields.append {RecordField "detail-amount-2",caption= "初回２"}}
{fields.append {RecordField "detail-amount-3",caption= "初回３"}}
else
{rgc.append {RecordGridColumn "row-header"}}
{rgc.append {RecordGridColumn "detail-amount-1"}}
{rgc.append {RecordGridColumn "detail-amount-2"}}
{rgc.append {RecordGridColumn "detail-amount-3"}}
{rgc.append {RecordGridColumn "detail-amount-4"}}
{fields.append {RecordField "row-header", caption = "", domain = String}}
{fields.append {RecordField "detail-amount-1",caption= "２回目１"}}
{fields.append {RecordField "detail-amount-2",caption= "２回目２"}}
{fields.append {RecordField "detail-amount-3",caption= "２回目３"}}
{fields.append {RecordField "detail-amount-4",caption= "２回目４"}}
}
{self.vb-detail-area.add
{RecordGrid width = {make-elastic}, height = 165px, name = "rg-detail-1", {splice rgc}}
}

set self.rg-detail-1 = {g "rg-detail-1"} asa RecordGrid
set self.rg-detail-1.record-source = {RecordSet {RecordFields {splice fields}}}
}